LAAS-CNRS, The University of Toulouse , 7 Avenue du colonel Roche, F-31077 Toulouse, France.
CEMES-CNRS, The University of Toulouse , 29 rue Jeanne Marvig, F-31055 Toulouse, France.
ACS Appl Mater Interfaces. 2016 May 25;8(20):13104-13. doi: 10.1021/acsami.6b02008. Epub 2016 May 11.
Nanoenergetic materials are beginning to play an important role in part because they are being considered as energetic components for materials, chemical, and biochemical communities (e.g., microthermal sources, microactuators, in situ welding and soldering, local enhancement of chemical reactions, nanosterilization, and controlled cell apoptosis) and because their fabrication/synthesis raises fundamental challenges that are pushing the engineering and scientific frontiers. One such challenge is the development of processes to control and enhance the reactivity of materials such as energetics of nanolaminates, and the understanding of associated mechanisms. We present here a new method to substantially decrease the reaction onset temperature and in consequence the reactivity of nanolaminates based on the incorporation of a Cu nanolayer at the interfaces of Al/CuO nanolaminates. We further demonstrate that control of its thickness allows accurate tuning of both the thermal transport and energetic properties of the system. Using high resolution transmission electron microscopy, X-ray diffraction, and differential scanning calorimetry to analyze the physical, chemical and thermal characteristics of the resulting Al/CuO + interfacial Cu nanolaminates, we find that the incorporation of 5 nm Cu at both Al/CuO and CuO/Al interfaces lowers the onset temperature from 550 to 475 °C because of the lower-temperature formation of Al-Cu intermetallic phases and alloying. Cu intermixing is different in the CuO/Cu/Al and Al/Cu/CuO interfaces and independent of total Cu thickness: Cu readily penetrates into Al grains upon annealing to 300 °C, leading to Al/Cu phase transformations, while Al does not penetrate into Cu. Importantly, θ-Al2Cu nanocrystals are created below 63% wt Cu/Al, and coexist with the Al solid solution phase. These well-defined θ-Al2Cu nanocrystals seem to act as embedded Al+CuO energetic reaction triggers that lower the onset temperature. We show that ∼10 nm thick Cu at Al/CuO interfaces constitutes the optimum amount to increase both reactivity and overall heat of reaction by a factor of ∼20%. Above this amount, there is a rapid decrease of the heat of reaction.
纳米含能材料开始发挥重要作用，部分原因是它们被认为是材料、化学和生化领域的高能成分（例如，微热源、微致动器、原位焊接和钎焊、化学反应的局部增强、纳米杀菌和受控细胞凋亡），并且它们的制造/合成提出了推动工程和科学前沿的基本挑战。其中一个挑战是开发控制和增强材料反应性的方法，例如纳米层压板的能量学，以及理解相关机制。我们在这里提出了一种新方法，可以大大降低纳米层压板的反应起始温度，从而提高其反应性，该方法基于在 Al/CuO 纳米层压板界面处掺入 Cu 纳米层。我们进一步证明，通过控制其厚度，可以精确调整系统的热传输和能量特性。使用高分辨率透射电子显微镜、X 射线衍射和差示扫描量热法分析所得 Al/CuO+界面 Cu 纳米层压板的物理、化学和热特性，我们发现，在 Al/CuO 和 CuO/Al 界面处掺入 5nm Cu 可将起始温度从 550°C 降低至 475°C，这是因为形成了低温 Al-Cu 金属间化合物相和固溶体。Cu 在 CuO/Cu/Al 和 Al/Cu/CuO 界面处的混合方式不同，且与总 Cu 厚度无关：Cu 在退火至 300°C 时很容易渗透到 Al 晶粒中，导致 Al/Cu 相转变，而 Al 不会渗透到 Cu 中。重要的是，在低于 63%wt Cu/Al 时形成了θ-Al2Cu 纳米晶，并与 Al 固溶体共存。这些明确定义的θ-Al2Cu 纳米晶似乎充当嵌入式 Al+CuO 高能反应引发剂，从而降低了起始温度。我们表明，在 Al/CuO 界面处具有约 10nm 厚的 Cu 可以将反应性和总反应热提高约 20 倍。超过这个量，反应热会迅速下降。
